JPH0380053A - Method for heating food - Google Patents

Abstract

PURPOSE:To subject a solid food such as fruit, vegetable or meat or solid solution mixed food such as fruit-containing syrup to cooking and sterilization treatment by directly applying electricity to vegetable solid food having heat history and subjecting the food to resist heating. CONSTITUTION:A vegetable solid food having heat history of about >=40 deg.C is subjected to resist heating using a conductive liquid, preferably having dielectric constant not higher than that of the food as a medium.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention is directed to the application of electricity to solid foods such as fruits, canola, livestock meat, and fish meat, as well as solid-liquid mixed foods such as fruit syrup and Bee 7 stew. This invention relates to heating methods for cooking, sterilization, etc.

(Prior Art) Techniques have been proposed in which solid and/or liquid foods are subjected to electrical heating and resistance heating to perform cooking or sterilization treatment (for example, Japanese Patent Laid-Open No. 132138/1983, %
Publication No. 61-12270). This current-type food heating method performs internal heating using Joule heat, so the heating time is relatively short compared to external heating methods using normal heat conduction, and food quality such as flavor deteriorates due to heating. It has the advantage of being difficult to cause.

However, when electrical heating is applied to raw vegetable solid foods, the heating time is generally longer than that for liquid foods or animal solid foods, and uneven heating is more likely to occur.

As a countermeasure to this problem, Japanese Patent Application Laid-Open No. 60-251851 proposes a method in which grains such as soybeans are pretreated by soaking them in a salt-containing solution for several days to allow the salt to seep out evenly, and then heating with electricity. There is. Such pretreatment requires a long time, resulting in low productivity, and also causes the problem that the original taste of some foods may change due to the permeation of salt.

(Problems to be Solved by the Invention) The present invention solves the problem without substantially changing the original taste of food.
It is an object of the present invention to provide an electrical heating method for vegetable solid foods or solid-liquid mixed foods that can be heated uniformly at a relatively high heating rate.

(Means for Solving the Problems) The present invention is characterized in that electrical current is directly applied to a vegetable solid food having a heating history of about 40° C. or higher to resistance-heat the vegetable solid food. The present invention provides a method for heating a solid vegetable food (hereinafter referred to as the first invention).

Furthermore, the present invention is characterized in that a solid vegetable food having a heating history of about 40° C. or higher is resistance heated using a conductive liquid having a conductivity lower than that of the solid vegetable food as a medium. Method for heating vegetable solid food (hereinafter referred to as the second invention)
It provides:

Next, the present invention provides a solid-liquid product characterized in that a liquid food and a solid-liquid mixed food such as a vegetable solid food having a heating history of about 40° C. or higher are resistance-heated using the liquid food as a medium. The present invention provides a method for heating a mixed food (hereinafter referred to as the third invention).

In addition, the present invention provides a method in which an animal solid food and a vegetable solid food having a heating history of about 40°C or more are brought into contact with each other,
A method for heating a solid food (hereinafter referred to as the fourth invention) is provided, which is characterized in that both solid foods are resistance-heated by directly applying electricity to both solid foods. In this case, the animal solid food may be raw or may have a history of heating. The same applies to the following fifth and sixth inventions.

Furthermore, the present invention provides solid animal foods and solid vegetable foods having a heating history of about 400 or more.

A method for heating a solid food (hereinafter referred to as the fifth invention) characterized by resistance heating using a conductive liquid having a conductivity lower than that of the animal solid food and the vegetable solid food as a medium. This is what we provide.

Next, the present invention provides liquid foods, solid animal foods, and about 40
A method for heating a solid-liquid mixed food (5) (hereinafter referred to as 6th invention).

Here, a heating history of approximately 40°C or higher means that the entire solid vegetable food, including the vicinity of the center, has been heated to approximately 40°C or higher (preferably 30°C or higher).
8℃ or higher). The temperature immediately before resistance heating may be room temperature.

The upper limit of the heating temperature is lower than the resistance heating temperature, so it is limited by the resistance heating temperature required by the product.
Generally, the temperature is about 80° C. or less, more preferably 60° C. or less, and it is desirable for productivity and economy to keep the temperature as low as possible within the range of achieving the object of the present invention.

In this specification, the electrical conductivity of solid food refers to the value measured by the following method.

As shown in Figure 2, platinum electrode plates (12) were brought into contact with both ends of a 25°C food sample cut into 2-4 cm x 2-4 cm x 2-4 cm, and the impedance was measured using the 4-terminal method. The measurement was performed by applying a voltage of 50 Hz and 1 volt using a device.

(6) (Function) When raw solid plant foods are heated with electricity, the heating rate is relatively slow and uneven heating tends to occur because water in the raw state combines with polymers within the cells. Due to the fact that the ions are bound water with low conductivity, there is an electrical conduction barrier such as the cell wall, which is mainly composed of cellulose, which has relatively low conductivity, and there are air bubbles between the cells. It is assumed that this is because the conductivity is small as a whole because it is difficult to move, and the conductivity differs locally due to local structural differences.

When raw solid plant food is heated to about 40°C or higher, bound water is liberated and the air between cells expands, pushing the cells apart and damaging the cell walls, causing relatively large electrically conductive cell fluids to form. It is presumed that this is due to the flow of air into the intercellular spaces and the exclusion of air, but overall the ions become easier to flow and the conductivity increases, for example from 0.1 mS/L:nl to 5mS.
/m), the local structure difference in the residue is reduced, and the local difference in conductivity is also reduced. Therefore, in the case of the first invention, the vegetable solid food is heated with electricity relatively uniformly at a relatively high heating rate. It is thought that it will be possible to do so. Animal solid foods have a different cell structure from plant solid foods, so the above-mentioned problems are less likely to occur.

The second invention is preferably applied to solid vegetable foods that do not have relatively wide opposing planar surfaces that can be directly contacted with electrode plates due to their curved shape or small size.

That is, the current flows through the first electrode plate, - the conductive liquid - the solid vegetable food - the conductive liquid - the second electrode plate, i.e. the conductive liquid acts as a medium to transfer the solid vegetable food. Resistance heating.

At this time, since the electrical conductivity of the vegetable solid food is higher than that of the conductive liquid, the vegetable solid food is heated to the predetermined temperature 1 in a short time at a faster heating rate than the conductive liquid. Since the conductive liquid may be, for example, a saline solution with a low concentration of about 0.1 weight coefficient, there is almost no change in the original taste of the plant-based solid food.

In the case of the third invention, the liquid food serves as a medium to resistance-heat the solid vegetable food, and at the same time, the liquid food is also resistance-heated. In this case as well, the original taste of solid-liquid mixed foods changes or does not change when heated.

The electrical conductivity of solid animal foods, whether raw or heated, is generally about 1 to 10 mFJcm.
Normally, when heated, the electrical conductivity decreases slightly due to coagulation of proteins and exudation of liquid juice. The electrical conductivity of solid vegetable foods with a heating history of about 40°C or higher is generally about 1 to 10 mS/C.
rn, and is of the same order as that of animal solid foods.

Therefore, as in the fourth invention, animal solid foods, buttons and about 4
By bringing plant-based solid foods that have a heating history of 0°C or higher into contact with each other and applying electricity directly to both solid foods, preferably in series, both solid foods can be heated at a relatively high temperature. It can be heated uniformly at a heating speed.

If the electrical conductivity of the raw animal solid food is higher than that of the vegetable solid food that has a heating history of about 40°C, and the difference is relatively large, then the animal solid food has a heating history of about 40°C. When the electrical conductivity of the solid food is brought close to that of the solid vegetable food and then subjected to resistance heating, the heating is more uniform.

(9) As mentioned above, the electrical conductivity of the animal solid food and the vegetable solid food that has a heating history of about 40°C or higher is on the same order, so in the case of the fifth invention and the sixth invention, Both solid foods are resistively heated at approximately the same heating rate, relatively quickly and uniformly through the conductive liquid and liquid food medium, respectively.

In this case as well, if the electrical conductivity of the raw animal solid food is higher than that of the vegetable solid food that has a heating history of about 40°C, and the difference is relatively large, the animal solid food By giving a heating history and performing resistance heating in a state where the conductivities of both solid foods are close to each other, more uniform heating becomes possible.

(Example) The first invention is a vegetable solid food having opposing flat surfaces that can be contacted with an electrode plate, such as one-round sliced root vegetables (for example, carrots, radish, etc.). It is carried out in the manner shown in the figure. The current for resistance heating may be either alternating current or direct current, but usually commercial frequency alternating current is preferably used. The applied voltage is determined depending on the conductivity of the vegetable solid food and the target temperature (10).

As a heating method, internal heating by microwave irradiation, heating in hot water, steam heating, etc. are preferable.

When the first invention is applied to long-term storage of solid vegetable foods at room temperature, the sterilization temperature determined by the pH of the food (approximately 110
~130°C) in a pressure vessel in a sterile room for a predetermined period of time to obtain the required sterilization value (Fo), and then aseptically fill and seal the container (e.g., can or mouthpiece) using a conventional method. Let's do it.

The second invention is a vegetable solid food that does not have a relatively wide flat surface that can be contacted by an electrode plate, such as fruits (including cut pieces), beans, or root vegetables cut into dice shapes. good 1
Applicable properly. The conductive liquid must be hygienically harmless and is preferably one that does not impair the flavor of the solid vegetable food. Usually, a saline solution with a low concentration (for example, about 0.01 to 0.5% by weight) is preferably used.

When the second invention is applied to long-term storage of solid vegetable foods at room temperature, it is carried out using, for example, a sterilization heating-sterile packaging system as shown in FIG. In FIG. 1, l is a food tank, 2 is a pump, 3 is a continuous current heating tank, 4 is a cooler, 5 is an aseptic filling/sealing device, and 9 is a reflux pipe.

The heating tank 3 is made of, for example, a stainless steel tube with ceramic darting on the inner surface, and has a pair of electrode plates 6 facing each other on the inner surface.
, 6 are arranged, and the electrode plates 6, 6 are connected to an alternating current power source (not shown; for example, 300 volts, 50 Hz) by conductors (not shown).

The food tank 1 contains a vegetable solid food 7 that has a heating history of about 40°C or higher, that is, has been heated to about 40°C or higher and then cooled, for example, in a room temperature cabinet, and the solid food 7 has an electrical conductivity that is that of the solid food 7. For example, a conductive liquid 8 at room temperature is stored. The solid food 7 button and the conductive liquid 8 are continuously supplied from the food tank 1 to the energized heating tank 3 by the pump 2, and are sterilized by the current passed through the electrode plate 6 while passing through the heating tank 3. Resistance heating is carried out to a predetermined sterilization temperature (for example, 120° C. for solid food 7) for a time during which the value (Fo) is obtained (for example, several minutes for solid food 7).

Next, the solid food 7 and the conductive liquid 8 are cooled to near room temperature in the cooler 4, the conductive liquid 8 is refluxed through the food tank IK reflux pipe 9, and the solid food 7 is transferred to the aseptic filling and sealing device. 5 for packaged products such as canned goods.

Since the heating tank 3 is sealed, it can be pressurized as high as 1 atm, and therefore the solid food 7 can be heated and sterilized at, for example, 120°C. When the conductivity of the solid food 7 and the conductive liquid 8 are equal, t/i, the heating temperature of both is almost equal, but if the conductivity of the former is higher than that of the latter, the heating temperature of the latter is equal to that of the former. Yoji is also low. For example, the former is 1
At 20°C, the latter is, for example, about 80°C.

The third invention relates to solid vegetable foods and liquid foods such as boiled bamboo shoots and fruit syrup pickles (in the case of boiled bamboo shoots, water to which an appropriate amount of citric acid, etc. has been added corresponds to the liquid food). Applies to liquid mixed foods.

(13) In this case as well, when the product is used for long-term storage at room temperature, a sterilization heating-aseptic packaging system as shown in FIG. 1 is preferably employed. However, the reflux via "9" from the cooler to the food tank is not used.

In this case, the vegetable solid food button and the liquid food are heated with electricity at the same time, but since the conductivity of both is different, the heating time is the same, but the temperature of both after heating is different. Therefore, by heating with electricity, solid foods and liquid foods can be heated to a predetermined sterilization value (
The initial temperature (feeding temperature) of each food that will give the sterilization temperature that reaches Fo) is determined in advance through experiments, and the solid food and liquid food preheated to this initial temperature are heated in an energized heating tank. It is preferable to send it at 3.

The fourth invention is carried out in the same manner as the first invention, for example, by combining sliced root vegetables and cut beef into pieces.

The fifth invention is the same as the second invention, for example, in a combination of diced root vegetables and chopped pork (both may be in contact with each other or may be separated from each other). Implemented.

(14) The sixth invention provides foods such as beef stew and beef curry (
In this case, the roux becomes a liquid food), and is carried out in the same manner as in the third invention.

An experimental example will be described below.

Experimental Example 1 As shown in FIG. 2, platinum titanium electrode plates 12 were brought into contact with both ends of a sliced ginseng 11 having a diameter of approximately 35 mm and a length of 30 wn, and an alternating current of 100 volts and 50 Hz C+ was supplied from a source 13. Then, electricity was applied directly to Carrot 11. At that time, insert thermocouples (not shown) into the center part A of the central part in the length direction, the button in the upper part B (depth 5 mm from the surface), and the lower part C (depth 25 mm from the surface). Changes in the temperature of each part with the energization time were measured.

In hot water of about 100℃ for 3 minutes, the temperature of the center a becomes 40℃
Figure 3 (a) k shows the measurement results for carrots that were heated to a temperature of 100 ml (as confirmed with a thermocouple) and then left to cool at room temperature 1 (hereinafter referred to as warmed carrots) and fresh carrots. and (b). In the case of heated carrots, the amount of current applied is initially 0.
75A, terminal stage 2.4A, initial stage 0.
08A1 telophase was 3.3A.

For warmed carrots (conductivity 1.67), each part a and b.

It can be seen that the temperature rises uniformly in both cases and reaches about 110° C. after 180 seconds.

- In the case of pest ginseng (electrical conductivity 0.13), the effects of tissue differences depending on the location are noticeable, and the unevenness of temperature rise is noticeable.The temperature rise is fastest in the center part a, and The temperature rise in the lower part C was delayed, and in particular the lower part C did not reach 100°C. It should be noted that the reason why the temperature was observed to decrease after reaching the maximum temperature in each part is thought to be because the conductivity decreased due to evaporation of water, and the amount of current flowing decreased.

Experimental Example 2 As shown in Fig. 4, a rectangular parallelepiped-shaped daikon radish of 29w LIX29 resistance x 35 barrels was stored in a tank 17 with an internal volume of 300 c, such as a beer force, along with a saline solution 16 of 0.1 weight. Then, 100 holt and 50 h were applied to the electrode plate 18 made of platinum.
An alternating current was supplied from the power source 19 of Z, and the daikon radish 15 and the saline solution 16 were electrically heated.

The initial current amount is 1.85A for the heated radish described below.
.

Telophase 5. In the case of OA, raw radish, initial stage 1. OA, telophase 4.
It was 5A. Thermocouples (not shown) are inserted into the center part ab of the radish 15, a part b1 at a height of 5 mm from the bottom surface directly below it, and parts ck and d above and below the center part a in the saline solution, respectively. The temperature change with the energization time was measured.

Measurements on daikon radish heated to 45°C by microwave irradiation for 15 seconds in a household microwave oven (output 500 W) and then left to cool to room temperature (hereinafter referred to as heated radish) and raw radish The results are shown in FIGS. 5(a) and (b), respectively. Conductivity of button-warmed radish, fresh radish, and saline solution (25°C
) are 4, 4 mS/c1n, and 0.
08 mS/crn and 1.8 mS/cm.

In the case of warmed daikon radish, it is uniformly and rapidly added to the saline solution at
It can be seen that it is heated to 00°C or higher.

- In the case of the pest radish, the temperature rise was uneven in some parts, and internal cracks were observed near the center a where the temperature rise was rapid.

Experimental Example 3 (17) A sample with a length of 3.4 cm and a diameter of 2 was heated to 52°C by microwave irradiation for 10 seconds in a household microwave oven (output so ow), and then allowed to cool to room temperature. 20 warmed carrots cut into .8 cm rings (conductivity 3.6 rnS/lx)
), 0,1 weight factor (conductivity 1.8 ms/m) k
and 0.8% saline solution (conductivity 12.0 mS/c
rn) in the tank 17 shown in FIG. 4, and heated with electricity under the same conditions as in Experimental Example 2, and the temperature of each part a, b, and c was measured.

The measurement results when the saline concentration was 0.1 wt. and 0.8 wt. were shown in FIG. 6(a) and FIG. 6(b), respectively. 0. The electrical conductivity is greater than Warming Ginseng 20.
When using 8 weight polysaline solution as the heating medium (Fig. 6(b)
), it can be seen that the temperature of the saline solution rises faster than that of the carrots, and the heating rate of the carrots is much slower than that of the 0.1wt saline solution, and that the heating rate differs slightly depending on the part. .

Experimental Example 4 A rectangular parallelepiped potato 21 measuring 17 mm x 35 tran x 15 mm was heated with curry roux 22 (conductivity 14.
5mS/cfn) in the tank 17 in Fig. 4,
An alternating current of 50 (18) volts and 50 (18) Hz was supplied to heat the potatoes and curry roux. Thermocouples were inserted into the center part ab of the potato 21 and the part d of the curry roux 22 below it, and the temperature change in each part was measured with the time of energization. The amount of current applied was 4.5 A at the initial stage and 6.7 A at the final stage in the case of heated potatoes described below, and 35 A at the initial stage and 6.7 A at the final stage in the case of raw potatoes.

Warmed potatoes (conductivity 5.0 mS/Crn) that were heated to 42°C by microwave irradiation for 10 seconds in a household microwave oven (output 500 W) and then left to cool at room temperature 1, and raw potatoes ( The measurement results for conductivity (0.17 mS/crn) K are shown in FIGS. 7(a), 7(b), respectively.

In the case of warmed potatoes, it can be seen that the potatoes and roux are rapidly heated at approximately the same rate.

Experimental Example 5 Beef 24 was placed in an energizing tank 17 shown in FIG. 4 together with O11 salt water 16, and heated under the same conditions as in Experimental Example 2.

The center part ah of beef 2°4, the height of the bottom surface directly below it, the part b1 of rran, and the electrode plate 1 in the saline solution 16
Thermocouples were inserted into the upper parts e, b and lower part f between the tank wall 8 and the tank wall, and the temperature change in each part was measured with the energization time.

Heated beef boiled in water with a center part of 60CK (23m+
n x 28 mm x 30 mm; electrical conductivity 3.1
ms/m ) and raw beef of the same dimensions (conductivity 4.5
The measurement results for ms/z) are shown in Figure 8 (
Shown in a) and (b). It can be seen that in either case, the beef is heated uniformly and in a short time.

Experimental Example 6 A cubed beef 24 of 29 mm x 20 tran However, the same striped portion b1 as in Experimental Example 2, the upper portion e and the lower portion f (
A thermocouple was inserted into the tube (see FIG. 4) to measure the temperature change associated with the energization time of each part. The electrical conductivity of raw beef, heated beef that was heated in the same manner as in Experimental Example 5, and heated carrot that was heated in the same manner as in Experimental Example 1 was 4.5 mS/.
Cm, 3.1 ms/crnh and 1.67 m5/sub.

The measurement results for the combination of heated beef and heated carrots, and the combination of carcass and raw beef and heated carrots are shown in Figure 10 (a).
) button and (b).

It can be seen that the combination with heated beef, which has a smaller difference in electrical conductivity from heated carrots, results in more uniform heating as a whole and at a much higher rate.

(Effects of the Invention) According to the first interpolation and the fourth invention, there is an effect that the solid food is uniformly heated at a relatively high rate without substantially changing the original taste.

Therefore, despite being heated in a short time, it has the advantage that hard parts due to insufficient heating in some areas or crumbling parts due to excessive heating in certain areas are unlikely to occur.

In addition, the pretreatment of providing a heating history of about 40° C. or more is carried out in a relatively short time, so it has the advantage of high productivity.

The second stroke interval and the fifth invention have the above effects and merits (21
) It has the advantage of being able to efficiently perform resistance heating of solid foods of any shape or small size.

Also in the case of the third invention and the sixth invention, the above-mentioned effects and merits can be achieved with respect to the solid food that can be pressed into the form of a solid-liquid mixed food.

[Brief explanation of drawings]

FIG. 1 is an explanatory drawing of an example of a continuous heating device used for carrying out the second invention, FIG. 2 is a partially cutaway front view for explaining an example of a batch heating apparatus used for carrying out the first invention, 3(a) and 9(b) are diagrams showing the relationship between current application time and temperature when solid vegetable food is resistance heated using the apparatus shown in FIG. ) is a diagram for the present invention,
Figure 3(b) is a diagram for a comparative example, and Figure 4 is a diagram for a second example.
FIG. 5(a) and FIG. 6 are diagrams showing the relationship between energization time and temperature of an explanatory table of an example of a patch-type heating device used for implementing the third invention. (a) is a diagram for the present invention, (22) Figures 5 (b) and 6 (b) are diagrams for the comparative example, Figure 7 (a) p (b) Vi No. 4 FIG. 7(a) is a diagram showing the relationship between current application time and temperature when a solid-liquid mixed food is resistance heated using the apparatus shown in the figure; FIG. 7(a) is a diagram for the case of the present invention; b) is a diagram for a comparative example, FIG. 8(a). (b) is a diagram showing the relationship between current application time and temperature when solid animal food is resistance heated using the apparatus shown in Figure 4;
The figure is a front view showing the state in which animal solid food and vegetable solid food are brought into contact for resistance heating, Figure 1O (a) 9 (
b) is a diagram showing the relationship between current application time and temperature when the solid food in the state shown in FIG. 9 is resistance heated. 6... Electrode plate, 7... Solid food, 8... Conductive liquid, 11... Carrot (vegetable solid food), 12... Electrode plate, 24... Beef (animal) solid foods). (23) (a) Figure (b) Current application time (seconds) 0 20 +80 Current application time (seconds) (a) Figure 60 120 Time (seconds) 0 +20 180 Time (seconds) 40 2, Ω! ! l Residence ε kiss drive ε i: ω Kazu - Four Secrets 2 Decoy Secret & ! l! l Body?

Claims (7)

[Claims] (1) A method for heating a solid vegetable food, which comprises resistively heating the solid vegetable food by directly applying electricity to the solid vegetable food, which has a heating history of about 40° C. or higher. (2) A plant-based product characterized by resistance heating a plant-based solid food with a heating history of about 40°C or higher using a conductive liquid having a conductivity lower than that of the plant-based solid food as a medium. How to heat solid foods. (3) Heating of a solid-liquid mixed food characterized by resistance heating a liquid food and a solid-liquid mixed food consisting of a vegetable solid food with a heating history of about 40° C. or higher using the liquid food as a medium. Method. (4) Resistance heating of both solid foods by directly applying electricity to both animal solid foods and vegetable solid foods that have a heating history of approximately 40°C or higher while they are in contact with each other. A method for heating solid foods characterized by: (5) Animal solid foods and vegetable solid foods that have a heating history of approximately 40°C or higher must be treated with electrical conductivity that is less than that of the animal solid foods and the vegetable solid foods. A method for heating solid foods, characterized by resistance heating using a liquid as a medium. (6) A solid-liquid mixed food consisting of a liquid food, an animal solid food, and a vegetable solid food with a heating history of about 40°C or higher is resistance heated using the liquid food as a medium. Method for heating solid-liquid mixed foods. (7) The method for heating food according to claim (4), (5) or (6), wherein the solid animal food is raw or has a history of heating.